True color image from May 15, 2017 taken by the MODIS on NASA's Terra satellite. A plume of sediment from the Maumee River expends down the Ohio coast to Sandusky Bay. Small plumes are also evident around the smaller rivers. Shallow areas also show sediment stirred up from strong winds.
(NOAA)

The early projection on the likelihood of Harmful Algae Blooms (HABs) has just been issued by NOAA. Based on measurements taken so far this spring, and rainfall projections in the next month, this year is expected to be in the middle of the pack for HAB development.

Cumulative total bioavailable phosphorus loads for the Maumee River. Each line denotes a different year. 2017 is in red, and the solid red line is the measured load to May 15th. The likely range for the remainder of the loading season is the darker wedge, with heavy rain outcomes shown in the lighter red wedge.NOAA

Harmful Algae Blooms are the result of phosphorus in Lake Erie's water. Total bioavailable phosphorus(TBP) is the critical measurement. TBP is the sum of dissolved phosphorus, which is 100 percent available for HAB development, and a portion of particulate phosphorus that is available for HAB growth.

The graph just above shows the most likely amount of TBP this year will be in the mid-range of previous years. If additional very heavy rainfall doesn't occur in the next two months, 2017's chance for HAB on Lake Erie will also be "middle of the pack."

Project bloom compared to previous years. The wide red bar is the likely range of severity based on data from the last 15 years. The narrow red bar is the potential range of severity of HAB if additional heavy rain falls.NOAA

Knowing the current amount of phosphorus, and a projected additional amount, gives NOAA the chance to forecast HAB severity this summer. The graph above shows the projected bloom severity compared to the last 15 years. Notice the wide red bar is about in the middle on the severity scale to the left side of the graph. Also notice the potential upside of the severity index if additional heavy rain should fall in the next two months.

So right now it doesn't appear that it will be a terrible year for HAB on Lake Erie. However, the potential for HAB would increase dramatically if the heavy rain pattern shifts to northern Ohio and far southern Michigan.

NOAA will make updates to this forecast weekly through early July, giving us a feel for the increased potential of Harmful Algae Blooms on Lake Erie this summer.